File folders are known to take many different forms. They primarily consist of cardboard material which is folded twice, so that a front cover, a back cover and a spine are created. The folds between the spine and the covers are usually made like a double fold and are produced by rolling. The file folders can include many different extra features, for example finger holes, binder inserts, document files and the like. Files which are equipped with a fastening device usually have, on their front cover in the area of the corresponding fold, two longitudinal openings, each provided with a barb into which the clips of the fastener engage when the file is closed. As a result, these files are secured against unintentional opening.
A disadvantage of the known files is that, due to the elasticity of the material in the region of the fold, they have the tendency to open when they are closed and close when they are open. Both effects are extremely annoying. Due to the fact that the closed file has the tendency to open, it must be wedged between other objects on a shelf in order to stand securely. Due to the closing tendency of the open file, the front cover must be continuously weighted when working in the file. Although the unintentional opening of the closed file can be prevented with aid of the aforementioned openings in connection with the two clips of the file, this only works in files having this type of clip mechanism and not in all other filing systems. Moreover, the tendency of the open file to close is not diminished.
A further disadvantage of these known files is that they offer an unaesthetic and bulgy appearance when they are standing on a shelf or lying on a table. This is due to the fact that the folds are relatively wide and the spine has the tendency to curve.
In another type of file, the two covers and the spine are not made as one piece, but the file cover essentially consists of three separate plates. These three plates must be provided with a plastic cover which has weld seams in the vicinity of the fold. Although these files close and open neatly and also have a suitable appearance, they are nevertheless expensive to manufacture, on the one hand, since a complete plastic covering and welding cannot be omitted and the three parts must be joined to one another so as to fit exactly. Secondly, these files only have a slight wear resistance since the folds are only formed by the plastic foils of the front and back which have been welded together and this plastic weld seam quickly tears.